Question

this is the database link 1，有人可以帮我添加一个类似的计数器吗？请它应该显示no：of点赞并在点赞被收回时降低我的Java代码在

下面

length

这种增加类似于计数，但不减少，我希望它在单击时会减少

Answer 1

您的问题尚不完全清楚，但是，如果您尝试创建社交媒体帖子这样的功能，用户可以喜欢它，而与帖子不同，这可以提供帮助。

数据结构

Post-> postId -> likes -> 1 
              ...

您可以将其分为三个部分：

要显示帖子的点赞次数postId和当前用户userId1是否喜欢您的帖子

public void displayNumberOfLikes(String postId, String currentUserId){
    DatabaseReference likesRef = FirebaseDatabase.getInstance().getReference().child('Post').child(postId);
    likesRef.addValueEventListener(new ValueEventListener(){
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            if(dataSnapshot.exists()){
                long numOfLikes = 0;
                if(dataSnapshot.hasChild("likes")){
                    numOfLikes = dataSnapshot.child("likes").getValue(Long.class);
                }

                //Populate numOfLikes on post i.e. textView.setText(""+numOfLikes)
                //This is to check if the user has liked the post or not
                btnLike.setSelected(dataSnapshot.hasChild(userId));
            }
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });
}

像点击一样点击

public void onLikeClicked(View v, String postId, String userId){
    DatabaseReference likesRef = FirebaseDatabase.getInstance().getReference().child('Post').child(postId).child("likes");
    likesRef.addListenerForSingleValueEvent(new ValueEventListener(){
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            long numLikes = 0;
            if(dataSnapshot.exists()){
                numLikes = dataSnapshot.getValue(Long.class);
            }
            boolean isLiked = btnLike.isSelected();
            if(isLiked){
               //If already liked then user wants to unlike the post
               likesRef.set(numLikes-1);
            }else {
               //If not liked already then user wants to like the post
               likesRef.set(numLikes+1);
            }
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });
}

这样，您可以使用户喜欢和不喜欢帖子，并显示喜欢的总数。希望对您有帮助！

如何添加像计数器Android Studio Firebase

1 个答案: